Hazardous materials such as dioxin are included in exhaust gases generated by incinerating facilities, metal smelting facilities, and the like. Recently, it is urged to establish a simple and precise method for measuring an amount of dioxin included in the exhaust gas.
As a method for measuring the amount of dioxin included in the exhaust gas, it is possible to utilize ‘JIS K 0311’ regulated by Japanese Industrial Standards. In the method provided by ‘JIS K 0311’, both a solvent to dissolve the dioxin together with various materials included in the exhaust gas and an absorbing material to adsorb the dioxin together with the various materials are used to collect the dioxin, whereby the dioxin is extracted together with the other materials included in the exhausted gas. Therefore, in order to measure the amount of dioxin, it is necessary for recovering only the dioxin from the other dissolved material contained in the exhaust gas.
FIG. 16 shows a conventional recovery device.
The device includes a reservoir 601, and an adsorbing column 603 being communicated with a bottom of the reservoir 601. A filter material S2, such as silica gel, for collecting the materials contained in the solvent except the dioxin, and a sample holding material S1 for impregnating a solution thereto, the solution in which the materials included in the exhaust gas are dissolved, are packed sequentially into the reservoir 601 from the bottom thereof. The adsorbing column 603 is filled with an adsorbing material S3 for adsorbing the dioxin only, like activated carbon, alumina, etc.
In case of recovering the dioxin by using the device, a user impregnates the sample holding material S1 of the reservoir 601 with a specific volume of the sample liquid extracted as above, then, runs the solvent (hexane, in this case) therein from the top of the reservoir 601. The solvent elutes some materials including the dioxin through the filter material S2, and then runs down the adsorbing column 603. Since the adsorbing column 603 is filled with the adsorbing material S3, the adsorbing material S3 adsorbs the dioxin only, and the solvent is discharged from the bottom of the adsorbing column 603 to the outside.
After the solvent is drained out, as shown in FIG. 17, the user removes the adsorbing column 603 from the reservoir 601, turns the adsorbing column 603 upside down, and runs an eluant for dioxin therein from the top. The eluant is received by a recovery vessel 607. The eluant ran into the adsorbing column 603 is drained from the bottom of the adsorbing column 603 while dissolving the dioxin adsorbed on the adsorbing material S3.
The drained eluant is recovered by the recovery vessel as mentioned above, whereby it is possible to recover the eluant in which only the dioxin is dissolved.
Additionally, there is provided another device for recovering the material to be measured, by which the user can recover the eluant containing the dioxin only without the operations that the user turns the adsorbing column upside down and runs the solvent. The device is configured as shown in FIG. 18; the reservoir 601 and the adsorbing column 603 shown in FIG. 16 are connected by a tube 602 via two ports of a 3-way valve 606, and the other port of the 3-way valve is connected to a recovery pipe 605. Opening and closing the 3-way valve is controlled by a control unit as follows.
At pushing a start key of the device, the control unit controls the 3-way valve to communicate the reservoir 601 and the adsorbing column 603. Then the control unit runs the solvent into the reservoir 601 from the top. The injected solvent elutes plural kinds of materials containing the dioxin from the reservoir 601 through the filter material S2, like the solvent injected into the device shown in FIG. 16. When the solvent runs through the adsorbing column 603, the solvent allows the adsorbing material S3 filled in the adsorbing column 603 to adsorb the dioxin, and then drained out.
The control unit switches the 3-way valve 606 to communicate the adsorbing column 603 and the recovery pipe 605, and runs the eluant into the adsorbing column 603 from the bottom. The eluant elutes the dioxin collected by the adsorbing column 603, and runs into the recovery vessel 607 provided at an end of the recovery pipe 605 through the tube 602 to the recovery pipe 605.
Accordingly, the user can recover the eluant, in which only the dioxin is dissolved, by pushing the start key only.
However, in the dioxin recovery process made by the device shown in FIG. 18, when the solvent and the eluant in which dioxin is dissolved run through the 3-way valve 606, the dioxin is attached to the 3-way valve 606, and the 3-way valve 606 is contaminated with the dioxin. Therefore, whenever the recovery process is performed, the 3-way valve 606 needs to be cleaned.
The dioxin is adhered to and remains at the 3-way valve 606, with the result that this reduces the recovery percentage of the dioxin impregnated to the sample holding material S1. The contamination caused by the insufficient cleaning will reflect a bad influence on the next measurement.
Therefore, the present invention has an object to provide a device for recovering a material to be measured, wherein the material to be measured, such as the dioxin, can be recovered at high recovery percentage, and the cleaning of the valve is not required.